Some qualities of our sensory experience seem subject dependent, such as the color or size of an object's appearance. However, other qualities of our sensory experiences seem independent of our experiences, such as the fact that an object is spatial or shaped. This is the basic assumption of what many Early Modern Philosophers appealed to when trying to ground the real existence of the causes of our sensory experiences. I am just like hey wazzup to galileo in 1816 tho.
Galileo Galilei
(15 February, 1564 - 8 January, 1642)
Though most famous for his astronomical discoveries and experiments in physics, Galileo also laid a foundation for a revival of Epicurean belief in atomism, what the Early Moderns referred to as "Corpuscularianism". Corpuscularianism required the claim that though our sensory experiences did not resemble the fundamental aspects of reality, i.e. atoms, they were indirectly caused by these fundamental physical bodies. For instance, the feeling of "heat" is merely the motion of these particles:
It will be pleasantly warm or unpleasantly hot depending upon the number and the velocity (greater or lesser) of these pricking, penetrating particles...In sum, the operation of fire, considered in itself, is nothing but movement... (Galilei, The Assayer)
For Galileo, the properties of the atoms are the only real existing causes and thus are "primary". These properties include their shape, relative size, location, motion, solidity and number. However, the properties that are sensed are those which spring from these primary qualities and are known as "secondary": heat, color, taste, sound, and smell. The primary properties are defined by quantity, while the secondary properties are defined by quality. Galileo is making an argument to exclaim that the primary properties are the most important. In doing this, he is trying to undercut Aristotle's physics, which are based on quality rather than on quantity.
"I think, therefore, that these tastes, odors, colors, etc., [secondary properties] so far as their objective existence is concerned, are nothing but mere names for something which resides exclusively in our sensitive body (corpo sensitivo), so that if the perceiving creatures were removed, all of these quantities would be annihilated and abolished from existence." (Galilei, The Assayer)
Galileo gives the example of a statue to demonstrate the difference between primary and secondary qualities. He says that if he were to run his hand over a statue and a man in exactly the same matter, he would feel exactly the same kind of thing. However, the man would feel something that is not in the touch of the hand. If Galileo ran his hand under the arm pit, the man would feel the sensation of being tickled. However, this quality cannot be in the hand because when the hand is run over something like the stomach, there is no tickling sensation. He says in The Assayer, " (I)t seems to me that he would be gravely in error who would assert that the hand, in addition to movement and contact, intrinsically possesses another and different faculty which we might call the 'tickling faculty,'" He says that the tickling feeling is completely in the one being tickled as is taste, odor, color and so on.
John Locke
(29 August, 1632 – 28 October, 1704)
As ideas fill the blank universe of our fetal mind, qualities are, for Locke, powers in bodies which initially cause these ideas in us. There are two distinct causal powers in these external bodies: those which are inherent in the object and those which are inherent in our relation to the object. Those which are inherent, such as "solidity, extension, figure, and motion or rest, and number" are primary and cannot ever be considered as separate from external bodies themselves. Secondary properties, such as "colors, sounds, tastes, etc.", are not considered as part of bodies themselves, but are rather part of our sensory experiences of bodies. In other words, if there were no sensory experiences, there would be no secondary properties for Locke.
One shocking consequence of this distinction is the independence of primary and secondary qualities such that different secondary qualities might have just as well been produced by the primary qualities than the one's that we find in experience: a steel blade in one's flesh may have, in other words, induced feelings of pleasure were God to have so designed this connection.
One of Locke's arguments for this distinction depends on the example of "heat" discussed by Galileo. Locke notes a peculiar diverse quality of heat:
...the same fire that, at one distance produces in us the sensation of warmth, does at a nearer approach produce in us the far different sensation of pain. (II.viii.16)
Were warmth in the external object, such as a fire or hot kettle, then it would only cause the idea of (pleasurable) warmth, not the diverse ideas of (pleasurable) warmth and pain. But since these sensations of warmth and pain are dependent on the relations between the object and subject, the sensations themselves must be dependent on the subject.
Locke says that, "heat, whiteness or coldness, are no more in them than sickness or pain is in manna." (II.viii.17) All these secondary qualities that are perceived by the senses are not in inherently inside the objects themselves. If your eyes were not present to see the redness of an apple, the color would disappear because color is a secondary quality. However, the apple would retain its shape whether we take notice of it or not because shape is a primary quality that is directly in the object.
In addition to primary and secondary qualities, Lock says that there is a third quality, the power of an object. This is something in an object that allows it to effect another object, (ie the sun hurts our eyes if we stare at it.) He says that this power arises from the primary qualities much like the secondary qualities do. However, this power is not entirely dependent on the acting object as one would not say that a fair skinned person turned dark, we cannot say that it was the sun that turned dark.
George Berkeley
(12 March, 1685 – 14 January, 1753)
Berkeley's attack on the primary/secondary quality distinction substantiates his claim of idealism: that all of our ideas are not best accounted for as arising from an external source. In other words, for Berkeley, all qualities are secondary.
Attack on the Primary/Secondary Qualities Distinction!
Berkeley's fundamental insight is that the cause of our experiences are "immediate" or direct to our minds. Berkeley says, "In reading a book, what I immediately perceive are the letters, but mediately...are suggested to my mind the notions of God, virtue, truth, etc." (First Dialogue) Therefore, what you immediately perceive is what you gather from your senses, in this case, the letters on the page. What you immediately perceive is the words the letters form and their meaning as a whole.
And since ideas are the direct basis of all experience, (as Locke himself would agree, "Every man being conscious to himself that he thinks, and that which his mind is applied about while thinking being the ideas that are there." (An Essay Concerning Human Understanding, 1)], ideas are the cause of our experiences, not external objects. Whence the idea of "external object"? Berkeley convincingly argues that these ideas are gotten by reflection or "the deducing...of causes or occasions from effects and appearances, which alone are perceived by sense, [and] entirely relates to reason." (First Dialogue)
Galileo Galilei
(15 February, 1564 - 8 January, 1642)
Though most famous for his astronomical discoveries and experiments in physics, Galileo also laid a foundation for a revival of Epicurean belief in atomism, what the Early Moderns referred to as "Corpuscularianism". Corpuscularianism required the claim that though our sensory experiences did not resemble the fundamental aspects of reality, i.e. atoms, they were indirectly caused by these fundamental physical bodies. For instance, the feeling of "heat" is merely the motion of these particles:
It will be pleasantly warm or unpleasantly hot depending upon the number and the velocity (greater or lesser) of these pricking, penetrating particles...In sum, the operation of fire, considered in itself, is nothing but movement... (Galilei, The Assayer)
For Galileo, the properties of the atoms are the only real existing causes and thus are "primary". These properties include their shape, relative size, location, motion, solidity and number. However, the properties that are sensed are those which spring from these primary qualities and are known as "secondary": heat, color, taste, sound, and smell. The primary properties are defined by quantity, while the secondary properties are defined by quality. Galileo is making an argument to exclaim that the primary properties are the most important. In doing this, he is trying to undercut Aristotle's physics, which are based on quality rather than on quantity.
"I think, therefore, that these tastes, odors, colors, etc., [secondary properties] so far as their objective existence is concerned, are nothing but mere names for something which resides exclusively in our sensitive body (corpo sensitivo), so that if the perceiving creatures were removed, all of these quantities would be annihilated and abolished from existence." (Galilei, The Assayer)
Galileo gives the example of a statue to demonstrate the difference between primary and secondary qualities. He says that if he were to run his hand over a statue and a man in exactly the same matter, he would feel exactly the same kind of thing. However, the man would feel something that is not in the touch of the hand. If Galileo ran his hand under the arm pit, the man would feel the sensation of being tickled. However, this quality cannot be in the hand because when the hand is run over something like the stomach, there is no tickling sensation. He says in The Assayer, " (I)t seems to me that he would be gravely in error who would assert that the hand, in addition to movement and contact, intrinsically possesses another and different faculty which we might call the 'tickling faculty,'" He says that the tickling feeling is completely in the one being tickled as is taste, odor, color and so on.
John Locke
(29 August, 1632 – 28 October, 1704)
As ideas fill the blank universe of our fetal mind, qualities are, for Locke, powers in bodies which initially cause these ideas in us. There are two distinct causal powers in these external bodies: those which are inherent in the object and those which are inherent in our relation to the object. Those which are inherent, such as "solidity, extension, figure, and motion or rest, and number" are primary and cannot ever be considered as separate from external bodies themselves. Secondary properties, such as "colors, sounds, tastes, etc.", are not considered as part of bodies themselves, but are rather part of our sensory experiences of bodies. In other words, if there were no sensory experiences, there would be no secondary properties for Locke.
One shocking consequence of this distinction is the independence of primary and secondary qualities such that different secondary qualities might have just as well been produced by the primary qualities than the one's that we find in experience: a steel blade in one's flesh may have, in other words, induced feelings of pleasure were God to have so designed this connection.
One of Locke's arguments for this distinction depends on the example of "heat" discussed by Galileo. Locke notes a peculiar diverse quality of heat:
...the same fire that, at one distance produces in us the sensation of warmth, does at a nearer approach produce in us the far different sensation of pain. (II.viii.16)
Were warmth in the external object, such as a fire or hot kettle, then it would only cause the idea of (pleasurable) warmth, not the diverse ideas of (pleasurable) warmth and pain. But since these sensations of warmth and pain are dependent on the relations between the object and subject, the sensations themselves must be dependent on the subject.
Locke says that, "heat, whiteness or coldness, are no more in them than sickness or pain is in manna." (II.viii.17) All these secondary qualities that are perceived by the senses are not in inherently inside the objects themselves. If your eyes were not present to see the redness of an apple, the color would disappear because color is a secondary quality. However, the apple would retain its shape whether we take notice of it or not because shape is a primary quality that is directly in the object.
[Other Examples: Manna, Porphyry, Almond pounding]
In addition to primary and secondary qualities, Lock says that there is a third quality, the power of an object. This is something in an object that allows it to effect another object, (ie the sun hurts our eyes if we stare at it.) He says that this power arises from the primary qualities much like the secondary qualities do. However, this power is not entirely dependent on the acting object as one would not say that a fair skinned person turned dark, we cannot say that it was the sun that turned dark.
George Berkeley
(12 March, 1685 – 14 January, 1753)
Berkeley's attack on the primary/secondary quality distinction substantiates his claim of idealism: that all of our ideas are not best accounted for as arising from an external source. In other words, for Berkeley, all qualities are secondary.
Attack on the Primary/Secondary Qualities Distinction!
Berkeley's fundamental insight is that the cause of our experiences are "immediate" or direct to our minds. Berkeley says, "In reading a book, what I immediately perceive are the letters, but mediately...are suggested to my mind the notions of God, virtue, truth, etc." (First Dialogue) Therefore, what you immediately perceive is what you gather from your senses, in this case, the letters on the page. What you immediately perceive is the words the letters form and their meaning as a whole.
And since ideas are the direct basis of all experience, (as Locke himself would agree, "Every man being conscious to himself that he thinks, and that which his mind is applied about while thinking being the ideas that are there." (An Essay Concerning Human Understanding, 1)], ideas are the cause of our experiences, not external objects. Whence the idea of "external object"? Berkeley convincingly argues that these ideas are gotten by reflection or "the deducing...of causes or occasions from effects and appearances, which alone are perceived by sense, [and] entirely relates to reason." (First Dialogue)